1. Field of the Invention
This invention relates to a small-sized image sensor for reading information such as characters and symbols in a document, and a machine equipped with such an image sensor.
2. Description of the Related Art
It is currently known to have an image sensor for reading characters and symbols in a document by applying light onto the document from a light source in the form of an array of parallel light emitting elements such as LEDs and by receiving light reflected from the document by an array of light receiving elements which perform photoelectric conversion. Generally, this known image sensor comprises a light emitting element array, a light receiving element array, and an optical system for directing the light from the light emitting array to the document and then directing the reflected light from the document to the light receiving element array, the light emitting array being fixed to a substrate such as glass epoxy by soldering. The light receiving element array is formed by monolithic IC technology or the like, and is fixed to, for example, a ceramic substrate by an adhesive. The optical system is a rod array lens fixed to the frame of the image sensor at a desired position by screws.
Since the light emitting elements and the light receiving elements are supported on two separate substrates, this known image sensor must be assembled in an increased number of steps, which is laborious and expensive. To cope with this problems, it has been proposed to provide a light-path changing means between the light emitting element and the document and to mount both the light emitting element and the light receiving element on the same substrate.
However, in this prior arrangement in which the light-path changing means such as a mirror is located between the light emitting element and the document, since the distance between the light emitting element and the document is necessarily increased, an adequate amount of light can not be applied to the document, thus reducing the reading rate.